Noncaking potassium bromide for photographic developers



Patented May 19, 1953 UNITED: sTAres NoNoAKiNoro-mssmkfjiiadsiififi.iioitz, PHOTOGRAPHIO DEYELoPERs.

Edwin S. Wiitala and William J.- Rogers, Itocl ester, N. Y., assignorsto EastmanKodak'Coni: pany, Rochester, N. Y., a eel-pariah of'i'NewJersey N Drawing. Application March 28, 1952, Serial No. 279,208

6 Claims.

This invention relates to the prevention of oaking of potassium bromide,and more particularly to potassium bromide in which a desiccating agentwhich is compatible with photographic developers has been incorporated.Such agents impart non-caking properties to the potassium bromide.

Potassium bromide is an important component of most photographicdevelopers and acts essenbromide from which a component part is to beselected to be added to the developer mixture has to be broken up,granulated and screened. In fact, certain lots have been found to be sobadly caked that they have been totally rejected for use.

An object of the present invention is, therefore, to provide anon-caking potassium bromide which i suitable for employment inphotographic developer mixtures.

Another object of the invention is to provide a method of producing anon-caking potassium bromide.

In accordance with the invention we have discovered that the addition ofsmall. quantities of a desiccating agent, including one or more of thefollowing boron compounds, boric anhydride (B203) metaboric acid andorthoboric acids, have marked effect upon reducing the caking ofpotassium bromide. lhe potassium bromide and the desiccating agent maybe mixed together in any suitable manner. Quantities of desiccatingagent in an amount as small as /2% of the weight of potassium bromide isefiective in preventing caking. We have found that such small amounts ofthese desiccating agents when introduced into the developer formulationshave no effect .upon the photographic properties of the developer.Slight changes in the alkalinity of the developer formulation producedby the presence of these boron compounds can be adjusted by a minoradjustment of the alkaline component of the mixture. While these boroncompounds in an amount of /3 to 1% of the weight of potassium bromide tobe treated is preferred, amounts up to could be advantageously employed.

The invention will be further illustrated in the following examples:

Example 1 The advantages of the invention can be demonstrated asfollows: A sample of line granular, mesh, potassium bromide and asimilar sample containing 0.05% B203 were conditioned at F. for a weekwith intermittent heating and cooling to room temperature. The untreatedsample was caked and slightly discolored by this heating. The samplecontaining the B203 addition was found to be perfectly free flowing andto be unchanged in appearance.

Example 2 The procedure of Example 1 was repeated except that 1% byweight of boric anhydride was employed to overcome the caking tendencyof the potassium bromide. As in the first example, the untreated samplecaked but the treated sample was free flowing.

Example 3 The same procedure as in Example 1 was fol- Example 4 The sameprocedure as in Example 1 Was followed, except for the substitution of/g% orthoboric (H3803) for the boric anhydride. The potassium bromidecontaining the orthoboric acid was free flowing, while the check sampleof straight potassium bromide was moderately caked.

Our invention, therefore, is a desirable contribution to thephotographic developing art in that it permits saving of .materlalsandenables potassium bromide to be handled and combined with othercomponents of the photographic developers more easily.

What we claim and desire to secure by Letters Patent or the UnitedStates is:

l. A finely divided non-caking potassium bromide composition containingas an anti-caking agent 0.05% to 10% by weight of a compound selectedfrom the group consisting of boric anhydride, metaboric acid andorthoboric acids.

2. A. finely divided non-caking potassium bromide composition containingas an anti-caking agent 0.05% to 10% by weight of boric anhydride.

3. A finely divided non-caking potassium bromide composition containingas an anti-caking agent 0.05% to 10% by weight of metaboric acid.

4. A finely divided non-caking potassium bro- 3 '4 mide compositioncontaining as an anti-caking agent 0.05% to 10% by weight of orthoboricacid, References Cited in the file of this patent 5. The method ofpreventing caking Of finely UNITED STATES PATENTS divided potassiumbromide which comprises mixing therewith a small amount of a non-caking5 2 222 gsg a1 g g agent selected from the grou consisting of bone2,477,323 Wood July 1949 anhydride, metaboric acid and orthoboric acid.

6. The method of preventing caking of finely divided potassium bromidewhich comprises mixing therewith to 1% by weight of boric an- 10hydride.

EDWIN S. WIITALA. WILLIAM J. ROGERS.

5. THE METHOD OF PREVENTING CAKING OF FINELY DIVIDED POTASSIUM BROMIDEWHICH COMPRISES MIXING THEREWITH A SMALL AMOUNT OF A NON-CAKING AGENTSELECTED FROM THE GROUP CONSISTING OF BORIC ANHYDRIDE, METABORIC ACIDAND ORTHOBORIC ACID.